Imaging lens, and electronic apparatus including the same

ABSTRACT

An imaging lens includes first to sixth lens elements arranged from an object side to an image side in the given order. Through designs of surfaces of the lens elements and relevant optical parameters, a short system length of the imaging lens may be achieved while maintaining good optical performance.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese Application No.201410394789.3, filed on Aug. 12, 2014.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging lens and an electronicapparatus including the same.

2. Description of the Related Art

In recent years, as use of portable electronic devices (e.g., mobilephones and digital cameras) becomes ubiquitous, much effort has been putinto reducing dimensions of portable electronic devices. Moreover, asdimensions of charged coupled device (CCD) and complementary metal-oxidesemiconductor (CMOS) based optical sensors are reduced, dimensions ofimaging lenses for use with the optical sensors must be correspondinglyreduced without significantly compromising optical performance. Imagingquality and size are two of the most important characteristics for animaging lens.

Each of U.S. Pat. Nos. 8,355,215 and 8,432,619, and Taiwanese patentpublication no. 201337319 discloses an imaging lens with six lenselements. However, a system length of the imaging lens disclosed in eachof these patents is not sufficiently short to fit reduced thicknessdesign of current mobile phones.

Therefore, technical difficulties of a miniaturized imaging lens aremuch higher than those of traditional imaging lenses. Producing animaging lens that meets requirements of consumer electronic productswith satisfactory optical performance is always a goal in the industry.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an imaginglens having a shorter overall length while maintaining good opticalperformance.

According to one aspect of the present invention, an imaging lenscomprises a first lens element, a second lens element, a third lenselement, a fourth lens element, a fifth lens element and a sixth lenselement arranged in order from an object side to an image side along anoptical axis of the imaging lens. Each of the first lens element, thesecond lens element, the third lens element, the fourth lens element,the fifth lens element and the sixth lens element has a refractivepower, an object-side surface facing toward the object side, and animage-side surface facing toward the image side.

The first lens element has a positive refractive power. The object-sidesurface of the first lens element has a convex portion in a vicinity ofa periphery of the first lens element. The image-side surface of thefirst lens element has a convex portion in a vicinity of the opticalaxis.

The image-side surface of the second lens element has a concave portionin a vicinity of the optical axis.

The object-side surface of the third lens element has a convex portionin a vicinity of a periphery of the third lens element.

The object-side surface of the fourth lens element has a concave portionin a vicinity of the optical axis.

The object-side surface of the fifth lens element has a concave portionin a vicinity of the optical axis.

The image-side surface of the sixth lens element has a concave portionin a vicinity of the optical axis, and the sixth lens element is made ofa plastic material.

The imaging lens does not include any lens element with refractive powerother than the first lens element, the second lens element, the thirdlens element, the fourth lens element, the fifth lens element and thesixth lens element.

Another object of the present invention is to provide an electronicapparatus having an imaging lens with six lens elements.

According to another aspect of the present invention, an electronicapparatus includes a housing and an imaging module. The imaging moduleis disposed in the housing, and includes the imaging lens of the presentinvention, a barrel on which the imaging lens is disposed, a holder uniton which the barrel is disposed, and an image sensor disposed at theimage side of the imaging lens.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the embodiments withreference to the accompanying drawings, of which:

FIG. 1 is a schematic diagram to illustrate the structure of a lenselement;

FIG. 2 is a schematic diagram that illustrates the first embodiment ofan imaging lens according to the present invention;

FIG. 3 shows values of some optical data corresponding to the imaginglens of the first embodiment;

FIG. 4 shows values of some aspherical coefficients corresponding to theimaging lens of the first embodiment;

FIGS. 5(a) to 5(d) show different optical characteristics of the imaginglens of the first embodiment;

FIG. 6 is a schematic diagram that illustrates the second embodiment ofan imaging lens according to the present invention;

FIG. 7 shows values of some optical data corresponding to the imaginglens of the second embodiment;

FIG. 8 shows values of some aspherical coefficients corresponding to theimaging lens of the second embodiment;

FIGS. 9(a) to 9(d) show different optical characteristics of the imaginglens of the second embodiment;

FIG. 10 is a schematic diagram that illustrates the third embodiment ofan imaging lens according to the present invention;

FIG. 11 shows values of some optical data corresponding to the imaginglens of the third embodiment;

FIG. 12 shows values of some aspherical coefficients corresponding tothe imaging lens of the third embodiment;

FIGS. 13(a) to 13(d) show different optical characteristics of theimaging lens of the third embodiment;

FIG. 14 is a schematic diagram that illustrates the fourth embodiment ofan imaging lens according to the present invention;

FIG. 15 shows values of some optical data corresponding to the imaginglens of the fourth embodiment;

FIG. 16 shows values of some aspherical coefficients corresponding tothe imaging lens of the fourth embodiment;

FIGS. 17(a) to 17(d) show different optical characteristics of theimaging lens of the fourth embodiment;

FIG. 18 is a schematic diagram that illustrates the fifth embodiment ofan imaging lens according to the present invention;

FIG. 19 shows values of some optical data corresponding to the imaginglens of the fifth embodiment;

FIG. 20 shows values of some aspherical coefficients corresponding tothe imaging lens of the fifth embodiment;

FIGS. 21(a) to 21(d) show different optical characteristics of theimaging lens of the fifth embodiment;

FIG. 22 is a schematic diagram that illustrates the sixth embodiment ofan imaging lens according to the present invention;

FIG. 23 shows values of some optical data corresponding to the imaginglens of the sixth embodiment;

FIG. 24 shows values of some aspherical coefficients corresponding tothe imaging lens of the sixth embodiment;

FIGS. 25(a) to 25(d) show different optical characteristics of theimaging lens of the sixth embodiment;

FIG. 26 is a schematic diagram that illustrates the seventh embodimentof an imaging lens according to the present invention;

FIG. 27 shows values of some optical data corresponding to the imaginglens of the seventh embodiment;

FIG. 28 shows values of some aspherical coefficients corresponding tothe imaging lens of the seventh embodiment;

FIGS. 29(a) to 29(d) show different optical characteristics of theimaging lens of the seventh embodiment;

FIG. 30 is a table that lists values of relationships among some lensparameters corresponding to the imaging lenses of the first to seventhembodiments;

FIG. 31 is a schematic partly sectional view to illustrate a firstexemplary application of the imaging lens of the present invention; and

FIG. 32 is a schematic partly sectional view to illustrate a secondexemplary application of the imaging lens of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Before the present invention is described in greater detail, it shouldbe noted that like elements are denoted by the same reference numeralsthroughout the disclosure.

In the following description, “a lens element has a positive (ornegative) refractive power” means the lens element has a positive (ornegative) refractive power in a vicinity of an optical axis thereof. “Anobject-side surface (or image-side surface) has a convex (or concave)portion at a certain area” means that, compared to a radially exteriorarea adjacent to said certain area, said certain area is more convex (orconcave) in a direction parallel to the optical axis. Referring to FIG.1 as an example, the lens element is radially symmetrical with respectto an optical axis (I) thereof. The object-side surface of the lenselement has a convex portion at an area A, a concave portion at an areaB, and a convex portion at an area C. This is because the area A is moreconvex in a direction parallel to the optical axis (I) in comparisonwith a radially exterior area thereof (i.e., area B), the area B is moreconcave in comparison with the area C, and the area C is more convex incomparison with an area E. “In a vicinity of a periphery” refers to anarea around a periphery of a curved surface of the lens element forpassage of imaging light only, which is the area C in FIG. 1. Theimaging light includes a chief ray Lc and a marginal ray Lm. “In avicinity of the optical axis” refers to an area around the optical axisof the curved surface for passage of the imaging light only, which isthe area A in FIG. 1. In addition, the lens element further includes anextending portion E for installation into an optical imaging lensdevice. Ideally, the imaging light does not pass through the extendingportion E. The structure and shape of the extending portion E are notlimited herein. In the following embodiments, the extending portion E isnot depicted in the drawings for the sake of clarity.

Referring to FIG. 2, the first embodiment of an imaging lens 10according to the present invention includes an aperture stop 2, a firstlens element 3, a second lens element 4, a third lens element 5, afourth lens element 6, a fifth lens element 7, a sixth lens element 8and an optical filter 9 arranged in the given order along an opticalaxis (I) from an object side to an image side. The optical filter 9 isan infrared cut filter for selectively absorbing infrared light tothereby reduce imperfection of images formed at an image plane 100.

Each of the first, second, third, fourth, fifth and sixth lens elements3-8 and the optical filter 9 has an object-side surface 31, 41, 51, 61,71, 81, 91 facing toward the object side, and an image-side surface 32,42, 52, 62, 72, 82, 92 facing toward the image side. Light entering theimaging lens 10 travels through the aperture stop 2, the object-side andimage-side surfaces 31, 32 of the first lens element 3, the object-sideand image-side surfaces 41, 42 of the second lens element 4, theobject-side and image-side surfaces 51, 52 of the third lens element 5,the object-side and image-side surfaces 61, 62 of the fourth lenselement 6, the object-side and image-side surfaces 71, 72 of the fifthlens element 7, the object-side and image-side surfaces 81, 82 of thesixth lens element 8, and the object-side and image-side surfaces 91, 92of the optical filter 9, in the given order, to form an image on theimage plane 100. Each of the object-side surfaces 31, 41, 51, 61, 71, 81and the image-side surfaces 32, 42, 52, 62, 72, 82 is aspherical and hasa center point coinciding with the optical axis (I).

The lens elements 3-8 are made of a plastic material in this embodiment,and at least one of the lens elements 3-7 may be made of other materialsin other embodiments. In addition, each of the lens elements 3-8 has arefractive power.

In the first embodiment, which is depicted in FIG. 2, the first lenselement 3 has a positive refractive power. The object-side surface 31 ofthe first lens element 3 is a convex surface that has a convex portion311 in a vicinity of the optical axis (I), and a convex portion 312 in avicinity of a periphery of the first lens element 3. The image-sidesurface 32 of the first lens element 3 is a convex surface that has aconvex portion 321 in a vicinity of the optical axis (I), and a convexportion 322 in a vicinity of the periphery of the first lens element 3.

The second lens element 4 has a negative refractive power. Theobject-side surface 41 of the second lens element 4 is a convex surfacethat has a convex portion 411 in a vicinity of the optical axis (I), anda convex portion 412 in a vicinity of a periphery of the second lenselement 4. The image-side surface 42 of the second lens element 4 is aconcave surface that has a concave portion 421 in a vicinity of theoptical axis (I), and a concave portion 422 in a vicinity of theperiphery of the second lens element 4.

The third lens element 5 has a positive refractive power. Theobject-side surface 51 of the third lens element 5 is a convex surfacethat has a convex portion 511 in a vicinity of the optical axis (I), anda convex portion 512 in a vicinity of a periphery of the third lenselement 5. The image-side surface 52 of the third lens element 5 is aconvex surface that has a convex portion 521 in a vicinity of theoptical axis (I), and a convex portion 522 in a vicinity of theperiphery of the third lens element 5.

The fourth lens element 6 has a positive refractive power. Theobject-side surface 61 of the fourth lens element 6 is a concave surfacethat has a concave portion 611 in a vicinity of the optical axis (I),and a concave portion 612 in a vicinity of a periphery of the fourthlens element 6. The image-side surface 62 of the fourth lens element 6is a convex surface that has a convex portion 621 in a vicinity of theoptical axis (I), and a convex portion 622 in a vicinity of theperiphery of the fourth lens element 6.

The fifth lens element 7 has a positive refractive power. Theobject-side surface 71 of the fifth lens element 7 is a concave surfacethat has a concave portion 711 in a vicinity of the optical axis (I),and a concave portion 712 in a vicinity of a periphery of the fifth lenselement 7. The image-side surface 72 of the fifth lens element 7 is aconvex surface that has a convex portion 721 in a vicinity of theoptical axis (I), and a convex portion 722 in a vicinity of theperiphery of the fifth lens element 7.

The sixth lens element 8 has a negative refractive power. Theobject-side surface 81 of the sixth lens element 8 has a concave portion811 in a vicinity of the optical axis (I), and a convex portion 812 in avicinity of a periphery of the fifth lens element 8. The image-sidesurface 82 of the sixth lens element 8 has a concave portion 821 in avicinity of the optical axis (I), and a convex portion 822 in a vicinityof the periphery of the sixth lens element 8.

In the first embodiment, the imaging lens 10 does not include any lenselement with a refractive power other than the aforesaid lens elements3-8.

Shown in FIG. 3 is a table that lists values of some optical datacorresponding to the surfaces 31-91, 32-92 of the first embodiment. Theimaging lens 10 has an overall system effective focal length (EFL) of4.159 mm, a half field-of-view (HFOV) of 36.845°, an F-number of 1.995,and a system length of 5.351 mm. The system length refers to a distancebetween the object-side surface 31 of the first lens element 3 and theimage plane 100 at the optical axis (I).

In this embodiment, each of the object-side surfaces 31-81 and theimage-side surfaces 32-82 is aspherical, and satisfies the relationshipof

$\begin{matrix}{{Z(Y)} = {{\frac{Y^{2}}{R}/\left( {1 + \sqrt{1 - {\left( {1 + K} \right)\frac{Y^{2}}{R^{2}}}}} \right)} + {\sum\limits_{i = 1}^{n}{a_{2\; i} \times Y^{2\; i}}}}} & (1)\end{matrix}$

where:

R represents a radius of curvature of an aspherical surface;

Z represents a depth of the aspherical surface, which is defined as aperpendicular distance between an arbitrary point on the asphericalsurface that is spaced apart from the optical axis (I) by a distance Y,and a tangent plane at a vertex of the aspherical surface at the opticalaxis (I);

Y represents a perpendicular distance between the arbitrary point on theaspherical surface and the optical axis (I);

K represents a conic constant; and

a_(2i) represents an 2i^(th) aspherical coefficient.

Shown in FIG. 4 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thefirst embodiment.

Relationships among some of the lens parameters corresponding to thefirst embodiment are listed in a column of FIG. 30 corresponding to thefirst embodiment. Note that some terminologies are defined as follows:

T1 represents the thickness of the first lens element 3 at the opticalaxis (I);

T2 represents the thickness of the second lens element 4 at the opticalaxis (I);

T3 represents the thickness of the third lens element 5 at the opticalaxis (I);

T4 represents the thickness of the fourth lens element 6 at the opticalaxis (I);

T5 represents the thickness of the fifth lens element 7 at the opticalaxis (I);

T6 represents the thickness of the sixth lens element 8 at the opticalaxis (I);

G12 represents an air gap length between the first lens element 3 andthe second lens element 4 at the optical axis (I);

G23 represents an air gap length between the second lens element 4 andthe third lens element 5 at the optical axis (I);

G34 represents an air gap length between the third lens element 5 andthe fourth lens element 6 at the optical axis (I);

G45 represents an air gap length between the fourth lens element 6 andthe fifth lens element 7 at the optical axis (I);

G56 represents an air gap length between the fifth lens element 7 andthe sixth lens element 8 at the optical axis (I);

Gaa represents a sum of the five air gap lengths among the first,second, third, fourth, fifth and sixth lens elements 3-8 at the opticalaxis (I), i.e., the sum of G12, G23, G34, G45 and G56;

ALT represents a sum of the thicknesses of the first, second, third,fourth, fifth and sixth lens elements 3-8 at the optical axis (I), i.e.,the sum of T1, T2, T3, T4, T5 and T6;

TTL represents a distance between the object-side surface 31 of thefirst lens element 3 and the image plane 100 at the optical axis (I);

BFL represents a distance at the optical axis (I) between the image-sidesurface 82 of the sixth lens element 8 and the image plane 100; and

EFL represents the focal length of the imaging lens 10.

In addition, some referenced terminologies are defined herein, where:

G6F represents an air gap length between the sixth lens element 8 andthe optical filter 9 at the optical axis (I);

TF represents a thickness of the optical filter 9 at the optical axis(I);

GFP represents an air gap length between the optical filter 9 and theimage plane 100 at the optical axis (I);

f1 represents a focal length of the first lens element 3;

f2 represents a focal length of the second lens element 4;

f3 represents a focal length of the third lens element 5;

f4 represents a focal length of the fourth lens element 6;

f5 represents a focal length of the fifth lens element 7;

f6 represents a focal length of the sixth lens element 8;

n1 represents a refractive index of the first lens element 3;

n2 represents a refractive index of the second lens element 4;

n3 represents a refractive index of the third lens element 5;

n4 represents a refractive index of the fourth lens element 6;

n5 represents a refractive index of the fifth lens element 7;

n6 represents a refractive index of the sixth lens element 8;

ν1 is an Abbe number of the first lens element 3;

ν2 is an Abbe number of the second lens element 4;

ν3 is an Abbe number of the third lens element 5;

ν4 is an Abbe number of the fourth lens element 6;

ν5 is an Abbe number of the fifth lens element 7; and

ν6 is an Abbe number of the sixth lens element 8.

FIGS. 5(a) to 5(d) respectively show simulation results corresponding tolongitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefirst embodiment. In each of the simulation results, curvescorresponding respectively to wavelengths of 470 nm, 555 nm, and 650 nmare shown.

It can be understood from FIG. 5(a) that, since each of the curvescorresponding to longitudinal spherical aberration has a focal length ateach field of view (indicated by the vertical axis) that falls withinthe range of ±0.025 mm, the first embodiment is able to achieve arelatively low spherical aberration at each of the wavelengths.Furthermore, since the curves at each of the wavelengths of 470 nm, 555nm, and 650 nm are close to each other, the first embodiment has arelatively low chromatic aberration.

It can be understood from FIGS. 5(b) and 5(c) that, since each of thecurves falls within the range of ±0.15 mm of focal length, the firstembodiment has a relatively low optical aberration.

Moreover, as shown in FIG. 5(d), since each of the curves correspondingto distortion aberration falls within the range of ±1%, the firstembodiment is able to meet requirements in imaging quality of mostoptical systems.

In view of the above, even with the system length reduced down to below5.4 mm, the imaging lens 10 of the first embodiment is still able toachieve a relatively good optical performance.

FIG. 6 illustrates the second embodiment of an imaging lens 10 accordingto the present invention, which has a configuration similar to that ofthe first embodiment, and differs in some of the optical data, theaspherical coefficients and the lens parameters of the lens elements3-8. In addition, in the second embodiment, the object-side surface 41of the second lens element 4 has a convex portion 411 in a vicinity ofthe optical axis (I), and a concave portion 413 in a vicinity of theperiphery of the second lens element 4. The object-side surface 81 ofthe sixth lens element 8 is a concave surface that has a concave portion811 in a vicinity of the optical axis (I), and a concave portion 813 ina vicinity of the periphery of the sixth lens element 8. In FIG. 6, thereference numerals of the concave portions and the convex portions thatare the same as those of the first embodiment are omitted for the sakeof clarity.

Shown in FIG. 7 is a table that lists values of some optical datacorresponding to the surfaces 31-91, 32-92 of the second embodiment. Theimaging lens 10 has an overall system focal length of 4.445 mm, an HFOVof 34.934°, an F-number of 2.006, and a system length of 5.778 mm.

Shown in FIG. 8 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thesecond embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the second embodiment are listed in a column of FIG. 30corresponding to the second embodiment.

FIGS. 9(a) to 9(d) respectively show simulation results corresponding tolongitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesecond embodiment. It can be understood from FIGS. 9(a) to 9(d) that thesecond embodiment is able to achieve a relatively good opticalperformance.

Compared to the first embodiment, the second embodiment has betterimaging quality, and may have a higher yield rate since the secondembodiment is relatively easier to fabricate.

FIG. 10 illustrates the third embodiment of an imaging lens 10 accordingto the present invention, which has a configuration similar to that ofthe first embodiment, and differs in some of the optical data, theaspherical coefficients and the lens parameters of the lens elements3-8. In addition, in the third embodiment, the object-side surface 41 ofthe second lens element 4 has a convex portion 411 in a vicinity of theoptical axis (I), and a concave portion 413 in a vicinity of theperiphery of the second lens element 4. The image-side surface 62 of thefourth lens element 6 has a convex portion 621 in a vicinity of theoptical axis (I), and a concave portion 623 in a vicinity of theperiphery of the fourth lens element 6. The object-side surface 81 ofthe sixth lens element 8 is a concave surface that has a concave portion811 in a vicinity of the optical axis (I), and a concave portion 813 ina vicinity of the periphery of the sixth lens element 8. In FIG. 10, thereference numerals of the concave portions and the convex portions thatare the same as those of the first embodiment are omitted for the sakeof clarity.

Shown in FIG. 11 is a table that lists values of some optical datacorresponding to the surfaces 31-91, 32-92 of the third embodiment. Theimaging lens 10 has an overall system focal length of 4.251 mm, an HFOVof 36.166°, an F-number of 2.009, and a system length of 5.633 mm.

Shown in FIG. 12 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thethird embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the third embodiment are listed in a column of FIG. 30corresponding to the third embodiment.

FIGS. 13(a) to 13(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thethird embodiment. It can be understood from FIGS. 13(a) to 13(d) thatthe third embodiment is able to achieve a relatively good opticalperformance.

Compared to the first embodiment, the third embodiment has betterimaging quality, and may have a higher yield rate since the thirdembodiment is relatively easier to fabricate.

FIG. 14 illustrates the fourth embodiment of an imaging lens 10according to the present invention, which has a configuration similar tothat of the first embodiment, and differs in some of the optical data,the aspherical coefficients and the lens parameters of the lens elements3-8. In addition, in the fourth embodiment, the aperture stop 2 isdisposed between the first lens element 3 and the second lens element 4.The image-side surface 52 of the third lens element 5 has a concaveportion 523 in a vicinity of the optical axis (I), a concave portion 524in a vicinity of the periphery of the third lens element 5, and a convexportion 525 between the concave portions 523, 524. The fifth lenselement 7 has a negative refractive power, and the image-side surface 72thereof has a concave portion 723 in a vicinity of the optical axis (I),and a convex portion 722 in a vicinity of the periphery of the fifthlens element 7. The object-side surface 81 of the sixth lens element 8is a convex surface that has a convex portion 814 in a vicinity of theoptical axis (I), and a convex portion 812 in a vicinity of theperiphery of the sixth lens element 8. The image-side surface 82 of thesixth lens element 8 has a concave portion 821 in a vicinity of theoptical axis (I), a concave portion 823 in a vicinity of the peripheryof the sixth lens element 8, and a convex portion 824 between theconcave portions 821, 823. In FIG. 14, the reference numerals of theconcave portions and the convex portions that are the same as those ofthe first embodiment are omitted for the sake of clarity.

Shown in FIG. 15 is a table that lists values of some optical datacorresponding to the surfaces 31-91, 32-92 of the fourth embodiment. Theimaging lens 10 has an overall system focal length of 3.883 mm, an HFOVof 37.077°, an F-number of 2.366, and a system length of 4.727 mm.

Shown in FIG. 16 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thefourth embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the fourth embodiment are listed in a column of FIG. 30corresponding to the fourth embodiment.

FIGS. 17(a) to 17(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefourth embodiment. It can be understood from FIGS. 17(a) to 17(d) thatthe fourth embodiment is able to achieve a relatively good opticalperformance.

Compared to the first embodiment, the fourth embodiment has a shortersystem length, a greater HFOV and better imaging quality, and mayfurther have a higher yield rate since the fourth embodiment isrelatively easier to fabricate.

FIG. 18 illustrates the fifth embodiment of an imaging lens 10 accordingto the present invention, which has a configuration similar to that ofthe first embodiment, and differs in some of the optical data, theaspherical coefficients and the lens parameters of the lens elements3-8. In addition, in the fifth embodiment, the aperture stop 2 isdisposed between the first lens element 3 and the second lens element 4.The object-side surface 81 of the sixth lens element 8 is a convexsurface that has a convex portion 814 in a vicinity of the optical axis(I), and a convex portion 812 in a vicinity of the periphery of thesixth lens element 8. In FIG. 18, the reference numerals of the concaveportions and the convex portions that are the same as those of the firstembodiment are omitted for the sake of clarity.

Shown in FIG. 19 is a table that lists values of some optical datacorresponding to the surfaces 31-91, 32-92 of the fifth embodiment. Theimaging lens 10 has an overall system focal length of 3.880 mm, an HFOVof 37.063°, an F-number of 2.335, and a system length of 4.903 mm.

Shown in FIG. 20 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thefifth embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the fifth embodiment are listed in a column of FIG. 30corresponding to the fifth embodiment.

FIGS. 21(a) to 21(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefifth embodiment. It can be understood from FIGS. 21(a) to 21(d) thatthe fifth embodiment is able to achieve a relatively good opticalperformance.

Compared to the first embodiment, the fifth embodiment has a shortersystem length, a greater HFOV and better imaging quality, and mayfurther have a higher yield rate since the fifth embodiment isrelatively easier to fabricate.

FIG. 22 illustrates the sixth embodiment of an imaging lens 10 accordingto the present invention, which has a configuration similar to that ofthe first embodiment, and differs in some of the optical data, theaspherical coefficients and the lens parameters of the lens elements3-8. In addition, in the sixth embodiment, the aperture stop 2 isdisposed between the first lens element 3 and the second lens element 4.The object-side surface 81 of the sixth lens element 8 has a convexportion 814 in a vicinity of the optical axis (I), and a concave portion813 in a vicinity of the periphery of the sixth lens element 8. In FIG.22, the reference numerals of the concave portions and the convexportions that are the same as those of the first embodiment are omittedfor the sake of clarity.

Shown in FIG. 23 is a table that lists values of some optical datacorresponding to the surfaces 31-91, 32-92 of the sixth embodiment. Theimaging lens 10 has an overall system focal length of 3.909 mm, an HFOVof 37.029°, an F-number of 2.276, and a system length of 4.871 mm.

Shown in FIG. 24 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thesixth embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the sixth embodiment are listed in a column of FIG. 30corresponding to the sixth embodiment.

FIGS. 25(a) to 25(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesixth embodiment. It can be understood from FIGS. 25(a) to 25(d) thatthe sixth embodiment is able to achieve a relatively good opticalperformance.

Compared to the first embodiment, the sixth embodiment has a shortersystem length, a greater HFOV and better imaging quality, and mayfurther have a higher yield rate since the sixth embodiment isrelatively easier to fabricate.

FIG. 26 illustrates the seventh embodiment of an imaging lens 10according to the present invention, which has a configuration similar tothat of the first embodiment, and differs in some of the optical data,the aspherical coefficients and the lens parameters of the lens elements3-8. In addition, in the seventh embodiment, the aperture stop 2 isdisposed between the first lens element 3 and the second lens element 4.The object-side surface 41 of the second lens element 4 is a concavesurface that has a concave portion 414 in a vicinity of the optical axis(I), and a concave portion 413 in a vicinity of the periphery of thesecond lens element 4. The image-side surface 42 of the second lenselement 4 has a concave portion 421 in a vicinity of the optical axis(I), and a convex portion 423 in a vicinity of the periphery of thesecond lens element 4. The image-side surface 52 of the third lenselement 5 has a concave portion 523 in a vicinity of the optical axis(I), and a convex portion 522 in a vicinity of the periphery of thethird lens element 5. The object-side surface 81 of the sixth lenselement 8 is a concave surface that has a concave portion 811 in avicinity of the optical axis (I), and a concave portion 813 in avicinity of the periphery of the sixth lens element 8. In FIG. 26, thereference numerals of the concave portions and the convex portions thatare the same as those of the first embodiment are omitted for the sakeof clarity.

Shown in FIG. 27 is a table that lists values of some optical datacorresponding to the surfaces 31-91, 32-92 of the seventh embodiment.The imaging lens 10 has an overall system focal length of 3.881 mm, anHFOV of 37.164°, an F-number of 2.274, and a system length of 5.183 mm.

Shown in FIG. 28 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to theseventh embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the seventh embodiment are listed in a column of FIG.30 corresponding to the seventh embodiment.

FIGS. 29(a) to 29(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of theseventh embodiment. It can be understood from FIGS. 29(a) to 29(d) thatthe seventh embodiment is able to achieve a relatively good opticalperformance.

Compared to the first embodiment, the seventh embodiment has a shortersystem length, a greater HFOV and better imaging quality, and mayfurther have a higher yield rate since the seventh embodiment isrelatively easier to fabricate.

Shown in FIG. 30 is a table that lists the aforesaid relationships amongsome of the aforementioned lens parameters corresponding to the sevenembodiments for comparison. It should be noted that the values of thelens parameters and the relationships listed in FIG. 30 are rounded offto the third decimal place. When each of the lens parameters of theimaging lens 10 according to this invention satisfies the followingoptical relationships, the optical performance is still relatively goodeven with the reduced system length:

1. T4/T6≦1.2 and G34/T6≦0.8: Since the sixth lens element 8 has arelatively larger optical effective diameter, reduction of T6 is limiteddue to lens manufacturing techniques. On the other hand, since thefourth length element 6 has a relatively smaller optical effectivediameter, greater reduction in T4 is allowed, so that T4/T6 tends to besmall. Since reduction in G34 is advantageous to reducing thickness ofthe imaging lens 10, G34/T6 tends to be small. However, proper ratiosamong the lens parameters should be maintained while the thicknesses ofthe lens elements and the air gap lengths are reduced, so as to avoid acertain parameter from being too large, that may disfavor reduction ofthe overall system length, or to avoid a certain parameter from beingtoo small, that may result in difficulty in assembly. Preferably,0.2≦T4/T6≦1.2 and 0.1≦G34/T6≦0.8.

2. ALT/T2≦13.1: Since the second lens element 4 has a relatively smalleroptical effective diameter, T2 may be made to be thinner for reducingthe system length of the imaging lens 10. However, reduction in T2 islimited due to lens manufacturing techniques. In addition, since ALTcontributes to a large proportion of the system length of the imaginglens 10, smaller ALT is more favorable in the thin design of the imaginglens 10. Accordingly, ALT/T2 tends to be small. However, proper ratiosamong the lens parameters should be maintained while the thicknesses ofthe lens elements are reduced, so as to avoid a certain parameter frombeing too large, that may disfavor reduction of the overall systemlength, or to avoid a certain parameter from being too small, that mayresult in difficulty in assembly. Preferably, 9.5≦ALT/T2≦13.1.

3. ALT/G23≦11, T5/G23≦1.8 and T1/G23≦2.5: Since the image-side surface42 of the second lens element 4 has the concave portion 422 in avicinity of the optical axis (I), reduction in G23 is limited. On theother hand, reductions in ALT, T1 and T5 are advantageous in the thindesign of the imaging lens 10, so that ALT/G23, T5/G23 and T1/G23 tendto be small. However, proper ratios among the lens parameters should bemaintained while the thicknesses of the lens elements and the air gaplengths are reduced, so as to avoid a certain parameter from being toolarge, that may disfavor reduction of the overall system length, or toavoid a certain parameter from being too small, that may result indifficulty in assembly. Preferably, 3.5≦ALT/G23≦11, 0.3≦T5/G23≦1.8 and0.4≦T1/G23≦2.5.

4. T1/T3≦1.9, Gaa/T6≧1.8, ALT/T3≦7.7, T5/T3≦1.6, G12/T6≧0.2, T4/T3≦1.2and T5/G45≦7.1: The contours and the thicknesses of the lens elements,and the air gap lengths among the lens elements should be well arrangedto correct aberrations when reduction in the system length of theimaging lens 10 and good imaging quality are both required. Inconsideration of manufacturing difficulty for easier assembly and ahigher yield rate, proper ratios among the lens parameters should bemaintained while the thicknesses of the lens elements and the air gaplengths are reduced, so as to avoid a certain parameter from being toolarge, that may disfavor reduction of the overall system length, or toavoid a certain parameter from being too small, that may result indifficulty in assembly. Preferably, 0.5≦T1/T3≦1.9, 1.8≦Gaa/T6≦2.7,3.85≦ALT/T3≦7.7, 0.2≦T5/T3≦1.6, 0.2≦G12/T6≦0.7, 0.4≦T4/T3≦1.2 and1.5≦T5/G45≦7.1.

Although the design of an optical system is generally associated withunpredictability, satisfaction of the aforementioned relationships mayenable the imaging lens 10 to have reductions in the system length andthe F-number, to have wider field of view, to have enhancement ofimaging quality, or to have a relatively higher yield rate of assembly,thereby alleviating at least one drawback of the prior art.

To sum up, effects and advantages of the imaging lens 10 according tothe present invention are described hereinafter.

1. The first lens element 3 contributes to a portion of an overallpositive refractive power required for the entire set of the lenselements, thereby favoring reduction in the system length of the imaginglens 10. Moreover, by virtue of cooperation among the convex portion312, the convex portion 321, the concave portion 421, the convex portion512, the concave portion 611, the concave portion 711 and the concaveportion 821, imaging quality of the imaging lens 10 may be improved.

2. Through design of the relevant lens parameters, optical aberrations,such as spherical aberration, may be reduced or even eliminated.Further, through surface design and arrangement of the lens elements3-8, even with the system length reduced, optical aberrations may stillbe reduced or even eliminated, resulting in relatively good opticalperformance.

3. Through the aforesaid seven embodiments, it is evident that thesystem length of this invention may be reduced down to below 5.8 mm, soas to facilitate developing thinner relevant products with economicbenefits.

Shown in FIG. 31 is a first exemplary application of the imaging lens10, in which the imaging lens 10 is disposed in a housing 11 of anelectronic apparatus 1 (such as a mobile phone, but not limitedthereto), and forms a part of an imaging module 12 of the electronicapparatus 1.

The imaging module 12 includes a barrel 21 on which the imaging lens 10is disposed, a holder unit 120 on which the barrel 21 is disposed, andan image sensor 130 disposed at the image plane 100 (see FIG. 2).

The holder unit 120 includes a first holder portion 121 in which thebarrel 21 is disposed, and a second holder portion 122 having a portioninterposed between the first holder portion 121 and the image sensor130. The barrel 21 and the first holder portion 121 of the holder unit120 extend along an axis (II), which coincides with the optical axis (I)of the imaging lens 10.

Shown in FIG. 32 is a second exemplary application of the imaging lens10. The differences between the first and second exemplary applicationsreside in that, in the second exemplary application, the holder unit 120is configured as a voice-coil motor (VCM), and the first holder portion121 includes an inner section 123 in which the barrel 21 is disposed, anouter section 124 that surrounds the inner section 123, a coil 125 thatis interposed between the inner and outer sections 123, 124, and amagnetic component 126 that is disposed between an outer side of thecoil 125 and an inner side of the outer section 124.

The inner section 123 and the barrel 21, together with the imaging lens10 therein, are movable with respect to the image sensor 130 along anaxis (III), which coincides with the optical axis (I) of the imaginglens 10. The optical filter 9 of the imaging lens 10 is disposed at thesecond holder portion 122, which is disposed to abut against the outersection 124. Configuration and arrangement of other components of theelectronic apparatus 1 in the second exemplary application are identicalto those in the first exemplary application, and hence will not bedescribed hereinafter for the sake of brevity.

By virtue of the imaging lens 10 of the present invention, theelectronic apparatus 1 in each of the exemplary applications may beconfigured to have a relatively reduced overall thickness with goodoptical and imaging performance, so as to reduce cost of materials, andsatisfy requirements of product miniaturization.

While the present invention has been described in connection with whatare considered the most practical embodiments, it is understood thatthis invention is not limited to the disclosed embodiments but isintended to cover various arrangements included within the spirit andscope of the broadest interpretation so as to encompass all suchmodifications and equivalent arrangements.

What is claimed is:
 1. An imaging lens comprising a first lens element,a second lens element, a third lens element, a fourth lens element, afifth lens element and a sixth lens element arranged in order from anobject side to an image side along an optical axis of said imaging lens,each of said first lens element, said second lens element, said thirdlens element, said fourth lens element, said fifth lens element and saidsixth lens element having a refractive power, an object-side surfacefacing toward the object side, and an image-side surface facing towardthe image side, wherein: said first lens element has a positiverefractive power, said object-side surface of said first lens elementhas a convex portion in a vicinity of a periphery of said first lenselement, and said image-side surface of said first lens element has aconvex portion in a vicinity of the optical axis; said image-sidesurface of said second lens element has a concave portion in a vicinityof the optical axis; said object-side surface of said third lens elementhas a convex portion in a vicinity of a periphery of said third lenselement; said object-side surface of said fourth lens element has aconcave portion in a vicinity of the optical axis; said object-sidesurface of said fifth lens element has a concave portion in a vicinityof the optical axis; said image-side surface of said sixth lens elementhas a concave portion in a vicinity of the optical axis, and said sixthlens element is made of a plastic material; and said imaging lens doesnot include any lens element with refractive power other than said firstlens element, said second lens element, said third lens element, saidfourth lens element, said fifth lens element and said sixth lenselement, and wherein the imaging lens further satisfies G12/T6≧0.2,where G12 represents an air gap length between said first lens elementand said second lens element at the optical axis, and T6 represents athickness of said sixth lens element at the optical axis.
 2. The imaginglens as claimed in claim 1, satisfying T4/T6≦1.2, where T4 represents athickness of said fourth lens element at the optical axis.
 3. Theimaging lens as claimed in claim 2, further satisfying T1/T3≦1.9, whereT1 represents a thickness of said first lens element at the opticalaxis, and T3 represents a thickness of said third lens element at theoptical axis.
 4. The imaging lens as claimed in claim 2, furthersatisfying Gaa/T6≧1.8, where Gaa represents a sum of five air gaplengths among said first lens element, said second lens element, saidthird lens element, said fourth lens element, said fifth lens elementand said sixth lens element at the optical axis.
 5. The imaging lens asclaimed in claim 2, further satisfying ALT/T3≦7.7, where ALT representsa sum of thicknesses of said first lens element, said second lenselement, said third lens element, said fourth lens element, said fifthlens element and said sixth lens element at the optical axis, and T3represents the thickness of said third lens element at the optical axis.6. The imaging lens as claimed in claim 1, satisfying G34/T6≦0.8, whereG34 represents an air gap length between said third lens element andsaid fourth lens element at the optical axis.
 7. The imaging lens asclaimed in claim 6, further satisfying ALT/T2≦13.1, where ALT representsa sum of thicknesses of said first lens element, said second lenselement, said third lens element, said fourth lens element, said fifthlens element and said sixth lens element at the optical axis, and T2represents the thickness of said second lens element at the opticalaxis.
 8. The imaging lens as claimed in claim 6, further satisfyingT5/T3≦1.6, where T5 represents a thickness of said fifth lens element atthe optical axis, and T3 represents a thickness of said third lenselement at the optical axis.
 9. The imaging lens as claimed in claim 1,satisfying ALT/G23≦11, where ALT represents a sum of thicknesses of saidfirst lens element, said second lens element, said third lens element,said fourth lens element, said fifth lens element and said sixth lenselement at the optical axis, and G23 represents an air gap lengthbetween said second lens element and said third lens element at theoptical axis.
 10. The imaging lens as claimed in claim 9, furthersatisfying T4/T3≦1.2, where T4 represents the thickness of said fourthlens element at the optical axis, and T3 represents the thickness ofsaid third lens element at the optical axis.
 11. The imaging lens asclaimed in claim 9, further satisfying T1/T3≦1.9, where T1 representsthe thickness of said first lens element at the optical axis, and T3represents the thickness of said third lens element at the optical axis.12. The imaging lens as claimed in claim 9, further satisfyingALT/T2≦13.1, where T2 represents the thickness of said second lenselement at the optical axis.
 13. The imaging lens as claimed in claim 1,satisfying T5/G45≦7.1, where T5 represents a thickness of said fifthlens element at the optical axis, and G45 represents an air gap lengthbetween said fourth lens element and said fifth lens element at theoptical axis.
 14. The imaging lens as claimed in claim 13, furthersatisfying T5/G23≦1.8, where G23 represents an air gap length betweensaid second lens element and said third lens element at the opticalaxis.
 15. The imaging lens as claimed in claim 13, further satisfyingT1/G23≦2.5, where T1 represents a thickness of said first lens elementat the optical axis, and G23 represents an air gap length between saidsecond lens element and said third lens element at the optical axis. 16.An electronic apparatus comprising: a housing; and an imaging moduledisposed in said housing, and including an imaging lens as claimed inclaim 1, a barrel on which said imaging lens is disposed, a holder uniton which said barrel is disposed, and an image sensor disposed at theimage side of said imaging lens.